Glossary · Method
Randomized Controlled Trial (RCT)
The standard study design for testing whether a supplement actually does what it claims in humans.
Plain language
A real human experiment with a control group, dosed at a known amount, in a peer-reviewed publication. Anything weaker (animal studies, cell studies, single-arm trials) is suggestive at best.
Definition
A randomized controlled trial is a study design in which participants are randomly assigned to either an intervention group or a control group, with neither participants nor (ideally) researchers knowing the assignment until after the trial concludes. Random assignment minimizes selection bias and confounding. A double-blind RCT (both participants and researchers blinded) is the standard load-bearing evidence type for a supplement benefit claim.